As part of the project to develop and the NMR method in biochemical and biological systems we have used these techniques together with unltracentrifugation, difference UV spectroscopy and equilibrium dialysis methods to study the structure and conformation of phospholipase A2 of snake vemons and to investigate their properties such as monomer-dimer transitions and enzyme-metal interations. The current data show that the phospholipase A2 and N. naja stra venom exits predominantly in a dimeric form which binds two calcium ions with different binding affinities. Results of these studies reveal the hydrophobic nature of the active center of the enzyme and yield information about the amino acid residues which are near or the calcium binding site.